Yu Yue, Suh Han Gyeol, Roig Mercè, Agterberg Daniel F
Department of Physics, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin, 53201, USA.
Niels Bohr Institute, University of Copenhagen, DK-2100, Copenhagen, Denmark.
Nat Commun. 2025 Mar 26;16(1):2950. doi: 10.1038/s41467-025-57970-9.
Realizing two-dimensional (2D) altermagnets is important for spintronics applications. Here we propose a microscopic template for stabilizing 2D altermagnetism through Van Hove singularities that are coincident in both energy and momentum. These coincident Van Hove singularities are a generic consequence of non-symmorphic symmetries in nine 2D space groups. Due to nontrivial symmetry properties of the Hamiltonian, these coincident Van Hove singularities allow new hopping interactions between the Van Hove singularities that do not appear in analogous Van Hove singularity based patch models for cuprates and graphene. We show these new interactions can give rise to various weak coupling, and BCS-based instabilities, including altermagnetism, nematicity, inter-band d-wave superconductivity, and orbital altermagnetic order. We apply our results to quasi-2D organic κ-Cl in which altermagnetism is known to appear.
实现二维交替磁体对于自旋电子学应用至关重要。在此，我们提出一种微观模板，用于通过在能量和动量上都重合的范霍夫奇点来稳定二维交替磁性。这些重合的范霍夫奇点是九个二维空间群中非简单对称的一般结果。由于哈密顿量的非平凡对称性质，这些重合的范霍夫奇点允许在范霍夫奇点之间产生新的跳跃相互作用，而这些相互作用在基于范霍夫奇点的类似铜酸盐和石墨烯的补丁模型中并不出现。我们表明，这些新的相互作用可以引发各种弱耦合以及基于BCS的不稳定性，包括交替磁性、向列性、带间d波超导性和轨道交替磁序。我们将我们的结果应用于已知会出现交替磁性的准二维有机κ-Cl。
